1. Technical Field
The invention relates to mobile robots for responding to hazardous materials emergencies where humans cannot go, and particularly to a light weight and economical robot of this type which is capable of operating in an area containing combustible gases.
2. Background Art
The response to emergencies involving hazardous materials spills by human entry teams frequently exposes entry team personnel to toxic chemicals and explosive reactions. Despite the use of protective clothing, serious hazards exist during first entry situations in which the actual nature of the hazard and the chemicals involved may not be known.
Use of a self-powered, self-contained, remote-controlled robot in first entry situation would avoid these risks. However, in some instances the hazardous materials emergency can involve the release of combustible gases and/or vapors into the atmosphere. Such a situation would require a specialized robot whose operation in the combustible environment would not inadvertently ignite the gases or vapors. In addition, such a robot would have to be capable of relaying information to a remote operator about the nature and concentrations of the combustible gases. The design of a robot capable of operating in a combustible atmosphere and providing the aforementioned information presents many problems.
One problem concerns the motors used to move the various parts of the robot. For example those used in its wheels or treads, and those used in its manipulator arm. The motors must not create sparks which could ignite the combustible gases. There are explosion proof motors commercially available. However, such motors are typically large and heavy. The use of such motors would severely limit the usefulness of the robot. The robot must be small and light so that it can be moved with a minimal amount of energy and be able to maneuver in tight places. The robot will have to fit through doorways and around furniture and other obstacles that may be in the way. Accordingly, the use of bulky explosion-proof motors is precluded.
Another problem concerns the electronics typically found in remote-controlled robots. For instance, mechanical relay switching devices used in some circuits could create a spark and ignite the combustible gases in the atmosphere. Some stationary robots operate on a hydraulic-based system, rather than electrical motors and circuits. However, the equipment necessary to implement such a hydraulic-based system is typically too large and heavy. The same physical limitations that existed with the use of explosion-proof motors, would apply to a hydraulic robot, as well.
In addition, electronic devices for operating the robot are typically mounted on the exterior of the robot's frame, thereby being directly exposed to the atmosphere. This raises the issue of damage or equipment failure. The robot will be operated remotely in area where many obstacles may exist. Typically, the operator will be guiding the motion of the robot using cameras mounted on the robot. The atmosphere at the accident sight could be filled with smoke and gases which obscure visibility. In addition, the camera may be located such that certain portions of the accident sight can not be seen. Therefore, a real possibility exists that the robot could crash into obstacles, or objects could fall onto the robot. If the robot's electronic components were damaged, or should fail for some other reason, sparks could be generated which would ignite the combustible gases in the atmosphere.
Another problem exists concerning sensing devices used to detect and analyze combustible gases that may be present at the accident sight. Typically, the sensors available for such a task are separate units resembling a flashlight. They are intended to be carried by emergency response personnel to the accident site. However, it would not be desirable to hold such a sensing device at the end of the robot arm, since it might be broken by accidental impact due to the operator's difficulty in maneuvering the robot as described above.